This invention relates to a hydroelectric machine including a tube-type hydraulic turbine or pump having a bladed wheel which rotates about a horizontal axis and whose blades are encircled by, and secured to, a rim to which the rotor of a surrounding electrical machine is attached.
Swiss Pat. No. 347,253 discloses a machine of this type in which the blades are adjustable, and the rotating unit consisting of the rim and rotor is mounted by means of a running drum which is secured on the rim and is supported by circumferentially spaced, plain bearing segments. This kind of bearing arrangement is difficult to manufacture precisely, with the necessary tolerances, in cases where the diameter of the running drum may be quite large, for example, 2 to 12 meters. With such a large diameter, the unavoidable deformation of the rim attributable to dead weight, centrifugal forces and temperature changes must also be taken into account. Moreover, the high peripheral speeds at the rim (e.g. 150 meters per second) must be accommodated. In addition, this bearing arrangement is difficult to assemble.
German Pat. No. 676,483 discloses a machine of the type first mentioned in which the bladed wheel employs fixed blades. In this case, the bladed wheel and rim are mounted to rotate on a stub shaft which is secured to the guide blade lattice hub, and this hub, in turn, is connected with the surrounding tubular housing through the guide blades. This bearing scheme obviously is not suitable for machines in which the rim has a diameter on the order of 2 to 12 meters.